Chemically targeted control of downhole flow control devices

ABSTRACT

Systems and methods using enhanced flow control devices are described. The flow control devices can be selectively closed completely or have its effective flow area reduced to restrict production (or injection) by use of a chemical trigger mechanism. In addition, some of the systems described herein deploy specific targeted chemical tracers, dissolvable in the unwanted production fluid (e.g. water or gas). These chemical tracers once dissolved will enter the production stream and be identified at the surface. The identification will determine which segment of the completion is producing the unwanted fluid. According to some embodiments, an appropriate chemical trigger is placed, for example, by pumping down through the tubing and utilizing intelligent completion valve to place the chemical, or by spotting with coiled tubing and bullhead to the formation, or by other methods of chemical placement. The chemical trigger will only trigger the active chemical in the appropriate flow control device. This chemical will then change state—dissolve, create thermal reaction, create a pressure swell or expand—which in turn allows a mechanical device to shift position such that a valve in the flow control device closes, or reduces its flow by restricting the flow area by swelling/expansion of the active chemical.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/185,957, filed Jul. 19, 2011.

FIELD

This patent specification generally relates to downhole flow control andinjection devices. More particularly, this patent specification relatesto selective control of flow control and injection devices installed ina wellbore using targeted chemistry.

BACKGROUND

Intelligent and/or segmented completions such as staged fracturecompletions and/or multi-zone injection wells have been utilized quiteextensively in the oilfield since the late 1990's. Their application hasbecome more widespread since the 2004 oil price increase and worldwidetechnology acceptance. The main applications in the Middle East forintelligent completions' have been in controlling multi-lateralcompletions where each flow control valve is placed at the junction foreach lateral leg—often an open hole lateral. These types of intelligentcompletion applications allow a lateral to be choked back or shut-offshould unwanted production occur. This manipulation of the wellcompletion can be done without resorting to intervention through coiledtubing or tractor operations which are themselves inherently riskyoperations. Intelligent completions are conventionally operated by useof hydraulic or electric control lines run in with the completion,adding to the complexity of installation.

In parallel with this technology acceptance, passive inflow controlsystems, (hereinafter referred to as “ICD”s) and/or injection controlsystems have become extremely popular for open-hole long horizontalcompletions especially in locations such as in the Middle East carbonatereservoirs. The main drivers have been controlling fracture contributionto the wellbore and balancing for wellbore hydraulics effects in longhorizontal or deviated wells.

In addition selective segmented completions have been used widely tofacilitate the stimulation treatment of multi-zone and/or longhorizontal wells. In this case, the selectivity is provided by a seriesof valves that is actuated to direct stimulating fluids (acid, water,sand, proppant, polymer, solvents or other such fluids) for the purposeof selectively injecting into the specific segment of the well beingtargeted.

The ICD style of completion is often particularly attractive to theoperator and especially the drilling departments due to the relativelylow risk and cost of the installation phase. However the long-termbenefits of the passive inflow control completion system are compromisedshould water production enter the wellbore. The ICD will limit theproduction of water, but does not allow it to be effectively shut offwithout intervention. Similarly, current ICD type completions complicateaccess to the formation for treatments such as stimulation treatments,clay stabilization, water conformance injection etc.

In addition, an ICD is by default designed before installation phase.Once the ICD is in place, there is little chance to change itscharacteristics (flow versus pressure differential), and therefore theirsuccess relies on the accurate characterization of the formationconductivity with the borehole.

Attempts have been made to provide dissolvable members.Commonly-assigned U.S. Patent Application Publ. No. US2007/0181224discusses reactive alloy materials for targeted control. One compositionconsists essentially of one or more reactive metals in major proportion,and one or more alloying elements in minor proportion, with the provisosthat the composition is high-strength, controllably reactive, anddegradable under defined conditions. Compositions may exist in a varietyof morphologies, including a reactive metal or degradable alloyprocessed into an alloy of crystalline, amorphous or mixed structurethat may constitute the matrix of other compositions, for instance acomposite.

Other attempts have been made to provide dissolvable members to controldownhole fluid flow in oilfield applications. For example,commonly-assigned U.S. Patent Application Publ. No. 2009/0151949discusses self dissolvable alloys for perforating. U.S. PatentApplication Publ. No. 2004/0014607 discusses dissolvable encapsulationof chemicals for oilfield treatment purposes. Commonly-assigned U.S.Patent Application Publ. No. 2011/0067889 discusses a hydraulicregulating mechanism for disposal in a well. The mechanism includes adegradable metal based element and a swellable component for hydraulicregulation. The mechanism is configured for ease of setting and removalby allowing degrading of the metal based element upon exposure tocertain downhole conditions which may trigger shrinking of the swellablecomponent. Commonly-assigned U.S. Patent Application Publ. No.2011/0048743 discusses a dissolvable bridge plug configured withcomponents for maintaining anchoring and structural integrity for highpressure applications. Embodiments of the plug are configured such thatthese components may substantially dissolve to allow for ease of plugremoval following such applications. Commonly-assigned U.S. PatentApplication Publ. No. 2008/0210423 discusses circulated degradablematerial assisted diversion methods for well treatment in completedwells. Commonly-assigned U.S. Patent Application Publ. No. 2008/0105438discusses whipstocks and deflectors comprising a degradable composition.

All of the commonly-assigned patent applications identified above arehereby incorporated by reference herein.

SUMMARY

According to some embodiments, a method of chemically targeting controlof flow control devices installed in a wellbore is provided. The methodincludes introducing a chemical into a wellbore having a plurality offlow control devices installed therein; and causing actuation of asubset of the plurality of flow control devices with a chemical reactiondue to the presence of the introduced chemical at the flow controldevice. According to some embodiments, at least one flow control deviceis an inflow control device that controls fluid flowing into thewellbore from a zone of the subterranean formation. According to someother embodiments, at least one flow control device is an injection flowcontrol device that controls fluid flowing from the wellbore into a zoneof the subterranean formation. The flow control devices can be arrangedin a series within a portion of the wellbore, and the introducedtriggering chemical flows to each of the flow control devices so as toexpose at least a portion of each flow control device to the introducedchemical.

According to some embodiments, the triggering chemical dissolves amechanical stop retaining a choking member actuated with one or morespring members. According to some other embodiments, the introducedchemical causes an exothermic chemical reaction used to actuate achoking member. According to some other embodiments, the introducedchemical reacts with a material in the flow control device so as torelease a plurality of sealing members that seal one or more orifices ina flow control device. According to some other embodiments, theintroduced chemical causes swelling of portions within the flow controldevice so as to restrict fluid flow within the flow control device.

According to some embodiments a separate flowline can be provided todeliver the introduced chemical flows to each flow control device.According to some embodiments, chemical tracers can be used that areassociated with each flow control device and are released upon exposureto an undesirable fluid so that identification on the surface of thetracer can be used to indicate which flow control device should beactuated so as to reduce the amount of the undesirable fluid enteringthe wellbore.

According to some embodiments, a wellbore penetrating a subterraneanformation having a plurality of flow control devices installed thereinis provided that includes a first flow control device installed in thewellbore being actuable upon exposure to a first triggering chemical,but not upon exposure to a second triggering chemical; and a second flowcontrol device installed in the wellbore being actuable upon exposure tothe second triggering chemical, but not actuable upon exposure to thefirst triggering chemical.

According to some embodiments, the triggering chemical is encapsulatedin a material and is positioned upstream from the flow control device.The encapsulating material dissolves or reacts with an unwanted fluid soas to release the triggering chemical and automatically actuate the flowcontrol device. The encapsulating material can also contain a tracerthat is detectable on the surface so as to indicate the location of thesource of the unwanted fluid. According to some embodiments an indicatorchemical is provided that is released only upon actuation of the flowcontrol device, thereby indicating or confirming to an operator on thesurface that actuation of the device has occurred.

BRIEF DESCRIPTION OF THE FIGURES

The present disclosure is further described in the detailed descriptionwhich follows, in reference to the noted plurality of drawings by way ofnon-limiting examples of embodiments, in which like reference numeralsrepresent similar parts throughout the several views of the drawings,and wherein:

FIG. 1 illustrates an oilfield setting in which chemically targetedcontrol of downhole flow control devices is carried out, according tosome embodiments;

FIGS. 2A-C are quarter cut-away side-views showing some components of asystem for targeted control of downhole flow control devices, accordingto some embodiments;

FIGS. 3A-E illustrate the principle of activation for a control linesystem, according to some embodiments;

FIGS. 4A-E illustrate the principle of activation for a tubing bullheadbased system, according to some embodiments;

FIGS. 5A-B illustrate a flow control device having releasable sealingballs, according to some embodiments;

FIGS. 6A-B illustrate a flow control device having a chamber with amaterial that swells when in contact with a trigger chemical, accordingto some embodiments;

FIGS. 7A-B illustrate a flow control device having a choke sleevecontrolled by an exothermic chemical reaction, according to someembodiments;

FIGS. 8A-E are diagrams representing a basic horizontal well systemusing chemically targeted flow control devices, according to someembodiments;

FIG. 9 illustrates using chemically targeted flow control devices in amulti-lateral application with a non-intelligent motherbore completionaccording to some embodiments;

FIG. 10 illustrates using chemically targeted flow control devices in amulti-lateral application with an intelligent motherbore completion,according to some embodiments;

FIG. 11 illustrates using chemically targeted flow control devices in amulti-lateral application with a horizontal motherbore, according tosome embodiments;

FIG. 12 is a table that presents selected examples chemicals that can beused to provide selective triggering, according to some embodiments;

FIG. 13 illustrates an injection flow control device, according to someembodiments;

FIGS. 14A-B are quarter cut-away side-views showing some components of adownhole flow control device having an indicator chemical released toconfirm device actuation, according to some embodiments; and

FIGS. 15A-B are quarter cut-away side-views showing some components ofdownhole flow control devices having self-triggering capability,according to some embodiments.

DETAILED DESCRIPTION

The following description provides exemplary embodiments only, and isnot intended to limit the scope, applicability, or configuration of thedisclosure. Rather, the following description of the exemplaryembodiments will provide those skilled in the art with an enablingdescription for implementing one or more exemplary embodiments. It beingunderstood that various changes may be made in the function andarrangement of elements without departing from the scope of subjectdisclosure as set forth in the appended claims.

Specific details are given in the following description to provide athorough understanding of the embodiments. However, it will beunderstood by one of ordinary skill in the art that the embodiments maybe practiced without these specific details. For example, systems,processes, and other elements in the subject disclosure may be shown ascomponents in block diagram form in order not to obscure the embodimentsin unnecessary detail. In other instances, well-known processes,structures, and techniques may be shown without unnecessary detail inorder to avoid obscuring the embodiments. Further, like referencenumbers and designations in the various drawings indicate like elements.

Also, it is noted that individual embodiments may be described as aprocess which is depicted as a flowchart, a flow diagram, a data flowdiagram, a structure diagram, or a block diagram. Although a flowchartmay describe the operations as a sequential process, many of theoperations can be performed in parallel or concurrently. In addition,the order of the operations may be re-arranged. A process may beterminated when its operations are completed, but could have additionalsteps not discussed or included in a figure. Furthermore, not alloperations in any particularly described process may occur in allembodiments. A process may correspond to a method, a function, aprocedure, a subroutine, a subprogram, etc. When a process correspondsto a function, its termination corresponds to a return of the functionto the calling function or the main function.

Furthermore, embodiments of the subject disclosure may be implemented,at least in part, either manually or automatically. Manual or automaticimplementations may be executed, or at least assisted, through the useof machines, hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware or microcode, the programcode or code segments to perform the necessary tasks may be stored in amachine readable medium. A processor(s) may perform the necessary tasks.

According to some embodiments, an enhanced flow control device isprovided, that can be selectively closed completely or have itseffective flow area reduced to restrict production (or injection) by useof a chemical trigger mechanism. In addition, some of the systemsdescribed herein deploy specific targeted chemical tracers, dissolvablein the unwanted production fluid (e.g. water or gas). These chemicaltracers once dissolved will enter the production stream and beidentified at the surface. The identification will determine whichsegment of the completion is producing the unwanted fluid.

According to some embodiments, an appropriate chemical trigger isplaced, for example, by pumping down through the tubing and utilizingintelligent completion valve to place the chemical, or by spotting withcoiled tubing and bullhead to the formation, or by other methods ofchemical placement. The chemical trigger will only trigger the activechemical in the appropriate flow control device. This chemical will thenchange state—dissolve, create thermal reaction, create a pressure swellor expand—which in turn allows a mechanical device to shift positionsuch that a valve in the flow control device closes, or reduces its flowby restricting the flow area by swelling/expansion of the activechemical.

Several designs have being proposed that make a flow control devicereact automatically to produced water and/or gas (unwanted fluids) toshut off or restrict the flow from the given zone. However, such designsdo not provide any downhole information and due to the lack of downholecontrol, produced fluids can migrate from one segment to the othercausing the wrong zones of the wellbore to shut off. Furthermore, thedesigns are fixed at the time of installation and do not allow theoperator the choice to make a decision on how or which segment of thewell can be modified after the completion is installed in the wellbore.

In contrast, according to some embodiments, the techniques describedherein allow the operator to determine where unwanted fluids are comingfrom and react to those fluids by making a conscious decision to pumpthe required chemical trigger for the section of the well producingunwanted fluids to shut it off, or restrict its flow.

According to some embodiments the same type of chemical triggermechanism is used to open instead of shut a device, or adjust aninjection valve characteristics without intervening in the wellbore.

The devices described herein have particular application where it isvery risky or impossible to enter the wellbore with coiled tubing ortractors—i.e. extended reach wells, long horizontals, or multilaterallegs out from the motherbore. Conventional technology allows completiontubular and Inflow Control Devices (ICD's) to be run and dropped off inopen hole lateral legs across from the motherbore, but so far there arelimited ways to re-enter these laterals once completed and involveinherently risky intervention.

According to some embodiments, the devices described herein can be runstand-alone as a passive component (with the chemical trigger as anoption) or run in combination with an intelligent motherbore completionaffording more production sweep control into the wellbore.

According to some embodiments, a chamber that is made of acid solublematerial such as carbonate rock is installed in a well section. Thechamber contains pre-sized balls that can be released to plug the flowport of the flow control device. The release of the balls is done byinjecting an acid that dissolves the chamber. Other materials that canbe used for the construction of the chamber include plastic, organic andinorganic compounds that can be dissolved by specific fluids.

According to some other embodiments, an acid soluble material such ascarbonate rock is used for the cap/stopper of a spring loaded valve. Thevalve is set to be normally open when the cap is in place by compressingthe spring. An acid can be injected when desired to dissolve thecap/stopper and release the spring such that the valve will be in aclosed position. According to some embodiments, the valve is set to benormally closed when the cap is in place by compressing the spring. Anacid can be injected when desired to dissolve the cap/stopper andrelease the spring such that the valve will be in an open position.

According to some other embodiments, a chamber is attached to the flowcontrol device, or the chamber can be an integrated part of the flowcontrol device. The chamber may be made of material that can bedissolved by specific fluids such as acid. The chamber may contain achemical or chemicals that swell when reacting with a specific injectionfluid. As the material in the chamber swell, it fills and seals thechamber such that the valve is effectively shut. The swelling of thematerial in the chamber can be triggered by fluid adsorption, heat, orchemical reaction.

According to some other embodiments, a chamber resin, wax, or othermaterials with melting higher than the reservoir temperature is used.According to some embodiments, an exothermic reaction can be created bythe reaction between the injection fluid and the chamber to causetemperature increase beyond the melting of the filling materials in thechamber, such as resin. The melted material will fill the fluid flowpath, and solidify when the exothermic reaction ceases, to plug off theflow ports or valves. The flow ports or valves can be unplugged whenpumping heated fluid to melt the solidified material.

According to some other embodiments a single layer or multiple layers ofencapsulated catalysts embedded in resin fluids are used, which releaseafter the injection of certain solvents, to dissolve the encapsulatedlayer. The released catalysts will allow resins curing to solidify whichcan block a flowing channel.

According to some other embodiments, the exothermic chemical reactionsare used to significantly increase the initial internal volume. A valvecan be coupled to a reaction chamber to shut down by expansion.

According to some other embodiments, a flow control device has a chambercontaining mixed base-gel fluid, such as a guar-gel system orsurfactants. After injecting a metallic salt-crosslinker, a high viscousmaterial is created to block the flow channels. This system is alsoreversible. This high viscosity gel is degradable by injectingoxidizers. In other words, the closed channels can be re-opened.

According to some other embodiments, a screen flow control device isused which contains a mixture of a chemical or chemicals. Afterinjection with another mixture of a chemical or chemicals, it willproduce a lot of precipitates which reduce or block the screen flowcontrol device.

According to some other embodiments, a “hydrogel” is used which can beswelled or de-swelled using a range of different triggers such as pH,ionic strength, temperature and electromagnetic radiation.

According to some embodiments, the placement of the chemical can bethrough simple bullheading from the surface through the tubing, throughcoiled tubing to spot it at the nearest appropriate location or throughchemical injection control lines run with the completion.

According to some embodiments, the flow path connected to the valve orflow control device contains a permeable porous medium. The porous mediacan be blocked when desired by injecting a cake forming slurrycontaining fine particulates or/and fibers, or chemicals that react withthe porous medium to form precipitants which seal off the porous medium.Reversely, the flow capacity of the porous medium can be enhanced byinjecting a chemical that dissolve portions of the pore network.

FIG. 1 illustrates an oilfield setting in which chemically targetedcontrol of downhole flow control devices is carried out, according tosome embodiments. On the surface 110, is a coiled tubing truck 120located at a wellhead 112. A chemical tank 104, hold fluid which isbeing introduced into the wellbore 116 through the tubing 124. Tubing124 enters wellbore 116 via well head 112. At or near the lower end oftubing 124 is a bottom hole assembly (BHA), not shown.

A barefoot section 130 of wellbore 116 is shown having several producingzones. Each producing zone of the wellbore is hydraulically isolatedusing a number of packers, such as packers 126 and 128 which are used toisolate zone 132. Within each zone, a flow control device 136 is used toallow fluid to enter production tubing. A chemical tracer 134 isprovided to indicate the production of undesirable fluid from the zone132, which can be detected and identified on the surface 110. The flowcontrol devices such as device 136 can be selectively closed using achemical introduced from truck 120, as will be described in greaterdetail herein.

Data from truck 120 or otherwise gathered at the wellsite aretransmitted to a processing center 150 which includes one or morecentral processing units 144 for carrying out the data processingprocedures as described herein, as well as other processing. Processingcenter 150 also includes a storage system 142, communications andinput/output modules 140, a user display 146 and a user input system148. According to some embodiments, processing center 150 may be locatedin a location remote from the wellsite.

FIGS. 2A-C are quarter cut-away side-views showing some components of asystem for targeted control of downhole flow control devices, accordingto some embodiments. In FIG. 2A, packer devices 210 and 212 can bemechanical, hydraulic, hydrostatic or swell packers, and are set acrossa segment in the wellbore. Note that the wellbore can be a cased holeperforated or open hole wellbore. The packers 210 and 212 provideeffective hydraulic isolation between segment 214 and other producingsegments, such as neighboring segment 216.

Inflow Control Devices (ICD) 220 and 222 can be either choke based, orin conjunction with a spring allowing for a range of activation. EachICD device provides the necessary choking of the fluid flow to restrictproduction into the wellbore from the formation or injection out of awellbore into the formation. In FIG. 2A, the ICD 220 restrictsproduction into flow line 202 from segment 214, and ICD 222 restrictsproduction into flow line 202 from segment 216. Each ICD includes one ormore chokes, which control the flow through the ICD. This choke may beof variable or fixed nature. The variable choke design is likely to becontrolled by spring mechanical or hydraulic forces against a pistonexposed to the upstream fluid. In the case of FIGS. 2A-B, choke orificessuch as 224 a, 224 b and 224 c are spaced apart around the circumferenceof the ICD 220. Choke sleeve 226 of ICD 220 is a sleeve that shifts overthe chokes when activated and either closes off or restricts the fluidsflow through the ICD.

Chemical tracers 228 and 230 are provided for isolated segments 214 and216 respectively. The tracer technology is existing, and is a water orgas soluble chemical, which has a specific chemistry (sometimes referredto as a “DNA chemical tracer” even though real DNA is not identified).Tracers such as 228 and 230 are placed at different positions in thewellbore completion. Each position has a different, unique tracerchemical. Once the unwanted fluid passes into the wellbore, the tracerin that segment of the wellbore only is dissolved and the chemicals canbe detected and analyzed at surface. This will tell the operator whichsection of the wellbore the water or gas is coming from.

A mechanical stop device is built into each ICD and acts as a stopperfor a piston or other moving part. In FIG. 2B, stop device 244 of ICD isa ring of material that acts as a stopper for choke sleeve 226 which isurged to towards the left by a coiled spring 240. The mechanical stopdevice 224 is retained in place or made of a chemical that is designedto change its state when contacted with a “trigger” chemical orcatalyst. Once triggered this stop device will either dissolve, react,create pressure or temperature, or expand to allow a mechanical device(a piston or other such device) to move to a position where it eithershuts in the choke, or restricts the size of the choke. In the case ofFIGS. 2A-C, stop device 244 dissolves so that it no longer retains thechoke sleeve 226 from moving to shut off the choke orifices.

A chemical trigger is a specific chemical designed to be pumped downholeand will react only with the targeted mechanical stop device asdescribed above. The trigger may be an acid, a solvent, a catalyst orother chemical designed which is able to withstand the pumping operationto place it in the wellbore or the wellbore conditions, and also avoidsdamaging the formation. Ideally this chemical should be limited involume to reduce unnecessary pumping or placement issues. In FIG. 2C,the trigger chemical that is specific to the stop device 244 hasdissolved the stop device and as a result the choke sleeve 226 is urgedto the left by coil spring 240 and covers the choke orifices such asorifices 224 a, 224 b and 224 c.

There are numerous examples of chemicals that could provide thedescribed “selective triggering” functionality. FIG. 12 is a table thatpresents selected examples chemicals that can be used to provideselective triggering, according to some embodiments. Table 1 listsseveral examples of “Base material”—which could be used in solidform—along with an example “trigger solvent” either non-polar, aproticor polar protic. Table 1 provides examples of which base materials arebest suited for deployment for selective triggering in a downholecompletion environment. The following abbreviations are used for Table1:

Y Base material is soluble in the solvent

PY Partially soluble in the solvent

N Base material is insoluble in the solvent

HT High Temperature

Polymers

PS polystyrene

PE polyethylene

HDPE High density polyethylene

LDPE Low density polyethylene

PVC polyvinyl chloride

PET Polyethylene terephthalates

PC Polycarbonate

PVDF Polyvinylidene Fluoride

Solvents

THF Tetrahydrofuran

DMF Dimethylformamide

DMAC Dimethylacetamide

TCB 1,2,4-trichlorobenzene

ODCB orthodichlorobenzene

DEE Diethyl ether

C-hexane Cyclohexane

DCM Dichloromethane

DMF Dimethylformamide

m-Cresol 3-methylphenol

DMSO Dimethyl sulfoxide

HCl Hydrochloric acid

HNO₃ Nitric acid

The examples listed in Table 1 is not an exhaustive list, but rather areexamples to provide a basis for one skilled in the art to selectspecific chemical “pairs” allowing this selectivity in triggering themto a different state. For example, one could use solid piece ofcarbonate rock as a stop device. This piece of carbonate can bedissolved by many kinds of inorganic and organic acids; such as HCl,H₂SO₄, HNO₃, CH₃COOH, HCOOH etc. Other alternatives include the use of apiece of solid polystyrene which can be dissolved by acetone. A furtherexamples is to utilise a piece of solid polyvinyl chloride (PVC) whichcan be dissolved by tetrahydrofuran.

FIGS. 3A-E illustrate the principle of activation for a control linesystem, according to some embodiments. Two zones 310 and 312 areillustrated to show the principle when water or other unwantedproduction fluid enters the production stream. In these examples it isassumed that oil is the production fluid, and water is the fluid to becontrolled. Packers 330 and 332 are used to hydraulically isolate thezones 310 and 312. Fluid from zone 310 enters the flow line 302 via ICD320 and fluid from zone 312 enters via ICD 322. In FIG. 3A, both zones310 and 312 are producing oil, as shown by the solid arrows, throughinflow control devices to balance or passively control productioninflow. In FIG. 3A, all zones are producing into the wellbore.

In FIG. 3B, zone 310 is producing water, as denoted by the broken-linearrows. Tracers 340 and 342 are soluble to water, since water is theundesirable fluid in this example. Tracer 340 therefore dissolves inwater and enters the production stream as denoted by droplets 340 a.Sampling of the fluids is done at surface to determine which tracer isbeing produced and therefore identifying that zone 310 is the watersource.

In FIG. 3C, a trigger chemical is selected to activate ICD 320 in zone310 only. This chemical will not affect the ICD 322 in zone 312 or ICD'slocated other zones. Trigger chemical can be spotted by bullheading,manipulation of control valves or spotting via coiled tubing and pumpedthrough the control line bypassing the segment packer and supplies thechemical directly to the inflow control devices. In the case of FIGS.3A-E, a control line 350 is used that bypasses the packers. In FIG. 3Dthe trigger chemical reacts with a specific chemical in ICD 320 andallows ICD 320 to activate. This could be for example, by dissolving amechanical stop device, as shown in and described with respect to FIGS.2A-C. ICD 320 activates to close off flow port in ICD 320. Zone 310 isnow isolated, while zone 312 is still able to produce. In FIG. 3E, thewell is put back on production. Zone 310 is isolated, and zone 312 isstill able to produce through inflow control device 322. The well nowproduces with lower water cut until such time as water encroacheswellbore at different position in reservoir.

FIGS. 4A-E illustrate the principle of activation for a tubing bullheadbased system, according to some embodiments. Although simpler to deploymechanically than a control line system as shown in FIGS. 3A-E, theoption shown in FIGS. 4A-E use more chemicals and fluids for triggering,and potentially result in more fluids being bullheaded into theformation. Care should be taken with this option to ensure the fluidreaches all segments. If any segment allows too much fluid into it, itis possible that the chemical trigger will not reach segments furtherdown the wellbore or lateral and therefore not activating theappropriate segment isolation mechanism. Two zones 410 and 412 areillustrated to show the principle when water or other unwantedproduction fluid enters the production stream. Packers 430 and 432 areused to hydraulically isolate the zones 410 and 412. Fluid from zone 410enters the flow line 402 via ICD 420 and fluid from zone 412 enters viaICD 422. In FIG. 4A, both zones 410 and 412 are producing oil, as shownby the solid arrows, through inflow control devices to balance orpassively control production inflow. In FIG. 4A, all zones are producinginto the wellbore.

In FIG. 4B, zone 410 is producing water, as denoted by the broken-linearrows. Tracers 440 and 442 are soluble to water, since water is theundesirable fluid in this example. Tracer 440 therefore dissolves inwater and enters the production stream as denoted by droplets 440 a.Sampling of the fluids is done at surface to determine which tracer isbeing produced and therefore identifying that zone 410 is the watersource.

In FIG. 4C, a chemical trigger is selected to activate ICD 420 in zone410 only. This chemical will not affect the ICD 422 in zone 412 or ICD'slocated other zones. The trigger chemical is spotted by bullheading,manipulation of control valves or spotting via coiled tubing and pumpedthrough the tubing and bullheads through the inflow control devices. InFIG. 4D the trigger chemical reacts with a specific chemical in ICD 420and allows ICD 420 to activate. This could be for example, by dissolvinga mechanical stop device, as shown in and described with respect toFIGS. 2A-C. ICD 420 activates to close off flow port in ICD 420. Zone410 is now isolated, while zone 412 is still able to produce. In FIG.4E, the well is put back on production. Zone 410 is isolated, and zone412 is still able to produce through inflow control device 422. The wellnow produces with lower water cut until such time as water encroacheswellbore at different position in reservoir.

Further detail regarding various activation and operating options willnow be provided, according to some embodiments. Many options exist forthe activation and chemical—mechanical mechanism to isolate theproduction.

Acid Soluble Cap/Stopper. According to some embodiments, the mechanicalstop shown in FIGS. 2B-C is an example where an acid soluble materialsuch as carbonate rock can be used as a cap or stopper of a springloaded valve. The valve is set to be normally open when the cap is inplace by compressing the spring. An acid can be injected when desired todissolve the cap/stopper and release the spring such that the valve willbe in a closed position.

Acid Soluble Material in Chamber. FIGS. 5A-B illustrate a flow controldevice having releasable sealing balls, according to some embodiments.Flow control device 500 has a cylindrical body through which fluidproduced from the production zone can flow into a production tubing 502.The produced fluid flows through an orifice plate 512 that includes anumber of uniformly sized orifices. Flow control device 500 is installedinto a well section, and includes an annular chamber 510 that is made ofan acid soluble material such as carbonate rock. The chamber 510contains pre-sized balls 520 that can be released to plug the orificesin plate 512 of the flow control device 500. According to someembodiments a control line 540 is used to direct the triggering chemicaldirectly to the chamber 510. According to other embodiments, thetriggering chemical can be bullheaded as described with respect to FIGS.4A-E. According to some embodiments, the release of the balls 520 isdone by injecting an acid that dissolves the chamber. According to otherembodiments, other materials can be used for the construction of thechamber including plastic, organic and inorganic compounds that can bedissolved by specific fluids. In FIG. 12, Table 1 gives a number ofalternative options of chemicals that could be deployed for such apurpose. Examples include a chamber made in aluminium and dissolved byacid such as HCl. Polyvinyl chloride chamber is resistant to HCl, butcan be dissolved by Tetrahydrofuran solvent. Polyethylene terephthalatechamber is soluble in phenol, chlorophenol, nitrobenzene and dimethylsulphoxide. It is insoluble in ether and in most other organic solvents.

FIG. 5B shows the flow control device 500 after the sealing balls havebeen released and are sealing the orifices on plate 512. According tosome embodiments, chamber 510 can contain a material having a lowmelting point and the triggering chemical can be designed to cause anexothermic chemical reactions, as is discussed in further detail below.

Chamber Soluble to Specific Trigger Chemicals or Catalysts. FIGS. 6A-Billustrate a flow control device having a chamber with a material thatswells when in contact with a trigger chemical, according to someembodiments. Flow control device 600 has a cylindrical body throughwhich fluid produced from the production zone can flow into a productiontubing 602. The produced fluid flows through the center surrounded by anannular chamber or region 610 that contains a chemical or chemicals thatwill swell when reacting with a specific injection fluid. The triggeringfluid can be directed to the chamber 610 via a control line 640 or itcan be bullheaded as is described with respect to FIGS. 4A-E. As thematerial in the chamber 610 swells, it fills and seals the chamber suchthat the valve is effectively shut, as shown in FIG. 6B. The swelling ofthe material in the chamber 610 can be triggered by fluid adsorption,heat, or chemical reaction. According to some embodiments, the chambercan be made of material that can be dissolved by specific fluids such asacid. Referring to FIG. 12, Table 1 lists potential chemical pairs—baseand trigger—that could be deployed for these examples.

Chamber with Material with Low Melting Point. Similar to the embodimentsdescribed with respect to FIGS. 6A-B, according to some embodiments aresin, wax, or other materials with melting higher than the reservoirtemperature in the chamber is used. An exothermic reaction can becreated by the reaction between the injection fluid and the chamber tocause temperature increase beyond the melting of the filling materialsin the chamber, such as resin. The melted material will fill the fluidflow path, and solidify when the exothermic reaction ceases, to plug offthe flow ports or valves. The flow ports or valves can be unplugged whenpumping heated fluid to melt the solidified material. According to someembodiments, the material melting can be used to release sealing ballsor other particles, such as described with respect to FIGS. 5A-B. Table1 of FIG. 12 lists potential chemical pairs—base and trigger—that couldbe deployed for these examples.

Single or Multiple Layer Catalysts. According to some embodiments, asingle layer or multiple layers of an encapsulated catalysts, areembedded in resin fluids which release after injecting certain solventsto dissolve the encapsulated layer. The released catalysts will allowresins to cure into a solid which can block a flowing channel. Thus, byusing encapsulation, the number of uniquely “addressable” orindividually targeted flow control devices or zones can be effectivelyincreased, given a set number of chemical reactions. Table 1 in FIG. 12lists potential chemical pairs—base and trigger—that could be deployedas encapsulated solids or fluids. After the encapsulation is destroyeddue to contact with a trigger chemical, the chemical within is releasedand can perform the function herein. One example is Epoxy Resin, inorder to convert epoxy resins into a hard material, it is necessary tocure the resin with hardener (catalyst). Epoxy resins cure quickly andeasily at practically any temperature from 5-150° C. depending on thechoice of hardener. The hardeners for epoxies include amines,polyamides, anhydrides, isocyanates, etc. For instance, anhydride can beencapsulated by polystyrene, and embedded in the epoxy resin. If it isdesirable to release anhydride, acetone can be pumped to dissolve theencapsulated layer. The released anhydride will be dispersed into epoxyresin, and allowed to cure into a solid.

Exothermic Reactions. Exothermic chemical reactions can be used tosignificantly increase an initial internal volume in for example, anenclosed chamber. A valve can be coupled to the reaction chamber to shutdown by the expansion. FIGS. 7A-B illustrate a flow control devicehaving a choke sleeve controlled by an exothermic chemical reaction,according to some embodiments. ICD 720 includes a number of chokeorifices such as orifices 724 a, 724 b and 724 c trough which fluid fromthe formation can enter the production tubing 702. A choke sleeve 726can slide over the orifices to shut off fluid flow, under the control ofa triggering chemical. A piston 744 is actuated by an exothermicchemical reaction in chamber 740. The exothermic reaction causes thechoke sleeve 726 to slide to the left so as to shut off fluid flowbetween the formation and tubing 702, as shown in FIG. 7B. Note thataccording to some embodiments, exothermic chemical reactions can be usedto melt material for use in devices such as described with respect toFIGS. 6A-B and FIGS. 5A-B.

According to some embodiments the ICD 720 is a pneumatically operatedvalve, and the introduced triggering chemical causes a reaction togenerate gas that actuates the pneumatic valve. Examples of gasgenerating reactions include acid (organic acids such as formic andacetic acid, or inorganic acids such as hydrochloric acid or nitricacid) reacting with sodium carbonate, sodium bicarbonate, or calciumcarbonate; sodium nitride (NaNO₂) reacting with sulfamic acid (HSO₃NH₂).

Mixed Base-Gel Fluid. According to some embodiments, a flow controldevice can be combined with a chamber that contains mixed base-gelfluid, such as a guar-gel system or surfactants. After injectingtypically a metallic salt-crosslinker, a highly viscous material iscreated to block the flow channels. This system is also reversible. Thishigh viscosity gel will be degradable by injecting oxidizers. In otherwords, the closed channels can be re-opened.

Further detail will now be provided for system architectures associatedwith chemically targeted control of flow control devices, according tosome embodiments. Many options exist for incorporation of the techniquesdescribed herein into a completion, from simple to highly complexintegrated completions.

FIGS. 8A-E are diagrams representing a basic horizontal well systemusing chemically targeted flow control devices, according to someembodiments. The upper completion 810 is illustrated as a simple tubingplus production packer, but could be any upper completion, either runseparately or in conjunction with the lower completion.

The lower completions 820 and 822 are shown in FIGS. 8A and 8Crespectively, and share a number of components in common. FIG. 8B showdetail for region 830 in completion 820, while FIGS. 8D and 8E showdetail for regions 840 and 850 respectively in completion 822. Isolationpackers such as 812 and 814 are used to hydraulically isolate adjacentsegments. Note that the lower completions 820 and 822 can be open holeor cased hole. For each isolated segment, an inflow control device (ICD)is provided such as ICDs 832, 834 and 828 in FIGS. 8A and 8B, and ICDs842, 844, 852 and 853 in FIGS. 8C, 8D and 8E. The inflow control deviceseach contain a mechanism to close or significantly reduce the flow areawhen triggered with a “trigger chemical” as described herein. Sandscreens such as screens 854 and 856 in FIG. 8E are optionally provided,for example in completions requiring sand control, in conjunction withthe system architectures shown. A flowing fluid “detector”—a tracerchemical placed in each isolated segment completion device that issoluble in a specific target fluid phase (e.g. water or gas), forexample, tracer chemicals 836 and 838 are shown in FIG. 8B, and tracerchemicals 846 and 848 are shown in FIG. 8D. Once that fluid phase startsto produce into the wellbore, the tracer will slowly dissolve into theproduction stream and be detected at surface by chemical analyses.

In the case of completion 820 shown in FIG. 8A, the “trigger chemical”or catalyst is pumped downhole by bullheading through the completiontubing 802 to all the inflow control devices in the lateral section. Thepumped chemical preferably contacts each and every one of the inflowcontrol devices in order to activate the target device. As such it isexpected that larger fluid volumes would be used. In addition, thisoption would obviate or make more complicated the use of check valves ineach of the inflow control devices.

FIG. 8C highlights an alternative and more economical system option,according to some embodiments, whereby the trigger chemical isbullheaded from surface or spotted just above the lower completion viacoiled tubing. Once the triggering chemical reaches the upper segmentthe chemical being pumped will bypass through the control line 842 whichpasses each and everyone of the inflow control valves. The triggerchemical or catalyst thus passes each of the valves. Only the targetvalve is activated by the pre-determined chemical reaction. The optionshown in FIG. 8C reduces the amount of trigger chemical requiredreducing potential formation damage making it more efficient, and allowsthe inflow control valves to contain a flow check mechanism eliminatingwellbore cross-flow.

FIGS. 9-11 illustrate multilateral completions using chemically targetedflow control devices, according to some embodiments. A significantadvantage of utilizing chemical catalysts or “triggers” to activate amechanical or hydraulic device, such as the inflow control devicesdescribed herein, is that it can be spotted and pumped easily intocomplex wellbores, such as multi-laterals. Intelligent completions inthe motherbore (see FIGS. 10 and 11) can be combined with chemicallyactivated lateral sections to allow a flexible, yet relatively simpledesign in getting fluid sensitivity and a measurement of segmentedcontrol into difficult to intervene lateral sections.

A chemically activated multilateral completion can also be designedwithout a need for intelligent completion components, for example as inFIG. 9, which illustrates using chemically targeted flow control devicesin a multi-lateral application with a non-intelligent motherborecompletion according to some embodiments. In certain circumstances,where chemical triggers can be spotted at the appropriate lateraljunction by coiled tubing or bullheading from surface to all laterallegs at the same time. In FIG. 9, the motherbore 910 is completed with asingle packer 900. Multiple lateral wellbores branch off of motherbore910 of which three are shown 920, 922 and 924. Each lateral can becompleted with casing, or openhole, as shown, as a perforated casedlateral, or as a combination of the two. Each lateral includes a numberof packers that are used to hydraulically isolate production zoneswithin the subterranean formation. Each isolated zone preferablyincludes a flow control device having both a chemical tracer andchemically triggered control of the flow, using one or more of thetechniques described herein. For example, in lateral 920, packers 912and 914 are used to isolate a zone 916 of the formation for productioninto tubing 904. The flow of fluid from the formation zone 916 into thetubing 904 is controlled using a flow control device 918 whichpreferably includes a chemical tracer sensitive to unwanted fluid, and achemically activated shut-off means such as described herein. Thetriggering chemical can be delivered using a control line 930 as shown,or it can be delivered through the production tubing 904. Some or all ofthe flow control devices can also be equipped with sand screens such asshown with flow control device 932.

FIG. 10 illustrates using chemically targeted flow control devices in amulti-lateral application with an intelligent motherbore completion,according to some embodiments. The motherbore 1010 has an intelligentcompletion that includes packers 1040, 1042 and 1044 which hydraulicallyisolate inflow from laterals 1020, 1022 and 1024. The flow from eachlateral is controlled using inflow control valves 1050, 1052 and 1054.Alternatively, sliding sleeves can be used instead of the valves. Theintelligent completion in motherbore 1002 allows for control andmonitoring of individual lateral contributions. Each lateral 1020, 1022and 1024 can be completed with casing, or openhole, as shown, as aperforated cased lateral, or as a combination of the two. Each lateralincludes a number of packers that are used to hydraulically isolateproduction zones within the subterranean formation. Each isolated zonepreferably includes a flow control device having both a chemical tracerand chemically triggered control of the flow, using one or more of thetechniques described herein. For example, in lateral 1020, packers 1012and 1014 are used to isolate a zone 1016 of the formation for productioninto tubing 1004. The flow of fluid from the formation zone 1016 intothe tubing 1004 is controlled using a flow control device 1018 whichpreferably includes a chemical tracer sensitive to unwanted fluid, and achemically activated shut-off means such as described herein. Thetriggering chemical can be delivered using a control line 1030 as shown,or it can be delivered through the production tubing 1004 as describedherein. Some or all of the flow control devices can also be equippedwith sand screens such as shown with flow control device 1032.

FIG. 11 illustrates using chemically targeted flow control devices in amulti-lateral application with a horizontal motherbore, according tosome embodiments. The motherbore 1110 has an intelligent completion thatincludes packers 1140, 1142 and 1144 which hydraulically isolate inflowfrom laterals 1120, 1122 and 1124. The flow from each lateral iscontrolled using inflow control valves 1150, 1152 and 1154.Alternatively, sliding sleeves can be used instead of the valves. Theintelligent completion in motherbore 1102 allows for control andmonitoring of individual lateral contributions.

According to some embodiments, the structures, chemistry and techniquesdescribed herein are used for injection of fluids into the formation,instead of control of fluid flow from the formation. For example,injection devices can be used for fracturing or other stimulationprocedures, which can be selectively activated by use of a chemicaltrigger mechanism. The embodiments of all of the foregoing figures canbe adapted to operate in reverse—to selectively control injection offluid into the formation. Specific examples of injection devices areshown in FIGS. 2A, 2B, 3A and 3B in which the injection flow is shown indotted-line arrows. Another specific example of an injection flowcontrol device is shown in FIG. 13.

FIG. 13 illustrates an injection flow control device, according to someembodiments. Injection flow control device 1300 has a cylindrical bodythrough which injection fluid can flow from tubing 1302 into a zone 1304in the subterranean formation. The injection fluid flows through anorifice plate 1312 that includes a number of uniformly sized orifices.Flow control device 1300 includes an annular chamber 1310 that is madeof acid soluble material such as carbonate rock is installed into a wellsection. According to some embodiments, chamber 1310 contains a chemicalor chemicals that will swell when reacting with a specific injectionfluid, such as shown in and described with respect to FIGS. 6A-B.According to some other embodiments, the chamber 1310 contains pre-sizedsealing balls (not shown) that can be released to plug the orifices inplate 1312 of the flow control device 1300, such as shown in anddescribed with respect to FIGS. 5A-B. According to some embodiments acontrol line 1340 is used to direct the triggering chemical directly tothe chamber 1310. According to other embodiments, the triggeringchemical can be bullheaded as described with respect to FIGS. 4A-E.According to some embodiments, the release of the sealing balls is doneby injecting an acid that dissolves the chamber. According to otherembodiments, other materials can be used for the construction of thechamber including plastic, organic and inorganic compounds that can bedissolved by specific fluids. In FIG. 12, Table 1 gives a number ofalternative options of chemicals that could be deployed for such apurpose. According to some embodiments, a shrinkable material is used inchamber 1310 such that the injection flow control device 1300 isnormally closed (analogous to chamber 610 shown in FIG. 6 b), and theexposure to a triggering chemical causes the material in chamber 1310 toshrink and open such as shown FIG. 13.

According to some embodiments a combination of inflow control devicesand injection flow control devices are deployed in a wellbore and can beselectively triggered using introduced chemicals according to theteachings provided herein.

FIGS. 14A-B are quarter cut-away side-views showing some components of adownhole flow control device having an indicator chemical released toconfirm device actuation, according to some embodiments. Flow controldevice 1420 is similar in most respects to inflow control device 220 asshown in FIGS. 2A-C, and can also operate in injection mode, accordingto some embodiments. The device 1420 can be actuated in the same fashionas described with respect to device 220 in FIGS. 2A-C, namely, a triggerchemical is used to dissolve or react with stop device 244 such that thestop no longer retains the choke sleeve 1426. The choke sleeve 1426 isurged to the left by coil spring 240 such that it covers the chokeorifices 224 a, 224 b and 224 c. However according to these embodimentsa material containing a further chemical, “indicator chemical” 1450 isincluded in the choke sleeve. When the choke sleeve 1426 is in theclosed position, as shown in FIG. 14B, the chemical 1450 mixes with thewellbore fluids flowing in flowline 202 and can be detected upstream bysampling the production stream. This chemical 1450 is considered an“indicator” a specific device has physically actuated downhole, therebyproviding assurance to the operator that particular device has shifted(closed or open depending on configuration).

FIGS. 15A-B are quarter cut-away side-views showing some components ofdownhole flow control devices having self-triggering capability,according to some embodiments. Flow control devices 1520 and 1522 aresimilar in most respects or identical to inflow control devices 220 and222 as shown in FIG. 2A, and can also operate in injection mode,according to some embodiments. Specific chemical tracer chemicals 1552and 1554 are positioned as shown on the outer surface of the device asshown. The tracer chemicals are designed to be dissolved by or to reactwith the unwanted produced fluids such that the chemical is releasedinto the produced fluid stream and can be detected on the surfacethereby indicating the presence of the unwanted fluid at the particulardevice. Different chemical or unique chemical additives can be used touniquely identify which device or devices through which the unwantedfluids are starting to flow into the wellbore. For example, for watercontrol, the tracer chemical would be one in which water contacts it fora pre-determined period, degrades and dissolves and can be detected onthe surface (or elsewhere downstream).

According to some embodiments, the tracer chemical encapsulates aseparate trigger chemical which flows with the production stream to thecontrol device. In the example shown in FIGS. 15A-B, tracer chemical1552 encapsulates trigger chemical 1528, and tracer chemical 1554encapsulates trigger chemical 1530. The trigger chemical released isdesigned to trigger the actuation device, thereby automating the processof flow control. In the case of device 1520, trigger chemical 1528dissolves a stop device in device 1520 such that the choke sleeve 226slides to cover the choke orifices 224a and 224 b. Thus an operator onthe surface is notified via the tracer that a particular device isassociated with the production of the unwanted fluid, and the device isautomatically shut off by the encapsulated trigger chemical. Thus, thecapability for automatically actuated downhole devices is providedwithout the intervention or pumping of a trigger chemical, according tosome embodiments. This type of device could be considered an“autonomous” device as is generally understood by the industry.

According to some embodiments, the techniques of FIGS. 14A-B and 15A-Bcan be combined. For example, the indicator chemical 1450 can beincluded in the choke sleeves of the automatically triggered devices1520 and 1522. Thus an operator on the surface would obtain confirmationthat the automatically triggered device had in-fact been shut off.

While the subject disclosure is described through the above exemplaryembodiments, it will be understood by those of ordinary skill in the artthat modification to and variation of the illustrated embodiments may bemade without departing from the inventive concepts herein disclosed.Moreover, while the embodiments are described in connection with variousillustrative structures, one skilled in the art will recognize that thesystem may be embodied using a variety of specific structures.Accordingly, the subject disclosure should not be viewed as limitedexcept by the scope and spirit of the appended claims.

What is claimed is:
 1. A method of chemically targeting control of flowcontrol devices installed in a wellbore comprising: by an operator,selecting for actuation at least one of a plurality of flow controldevices previously installed in a wellbore, leaving at least one of saidplurality of flow control devices as non-selected for actuation;selecting a triggering chemical fluid configured to selectively triggeractuation of said flow control devices selected for actuation andconfigured not to trigger actuation of said flow control devicesnon-selected for actuation; flowing said selected triggering chemicalfluid from a surface location through the wellbore and to expose bothsaid flow control devices selected for actuation and said flow controldevices non-selected for actuation to said triggering chemical fluid;selectively triggering actuations of said flow control devices selectedfor actuation, said actuations being caused by one or more chemicalreactions resulting from exposure with said triggering chemical fluid,leaving un-actuated said flow control devices non-selected despite beingexposed to said triggering chemical fluid.
 2. A method according toclaim 1 wherein the introduced chemical causes an exothermic chemicalreaction used to actuate a choking member.
 3. A method according toclaim 1 wherein at least one of the plurality of flow control devicesincludes a pneumatic valve, and the introduced chemical causes areaction to generate gas to actuate the pneumatic valve.
 4. A methodaccording to claim 3 wherein the gas generating reaction includes anacid reacting with one or more substances selected from a groupconsisting of sodium carbonate, sodium bicarbonate, calcium carbonateand sodium nitride (NaNO₂).
 5. A method according to claim 1 wherein theintroduced chemical reacts with a material in the flow control device soas to release a plurality of sealing members that seal one or moreorifices in flow control device.
 6. A method according to claim 5wherein the sealing members are spherical in shape.
 7. A methodaccording to claim 5 wherein the sealing members are of irregular shape.8. A method according to claim 1 wherein the introduced chemical causesswelling of portions within the flow control device so as to restrictfluid flow within the flow control device.
 9. A method according toclaim 1 wherein the introduced chemical is located downhole and isautomatically released in the presence of an unwanted fluid, therebyautomatically actuating the subset of the plurality of flow controldevices without further human intervention or control.
 10. A methodaccording to claim 9 wherein the induced chemical is encapsulated in amaterial that reacts or dissolves in the presence of the unwanted fluid,and the encapsulating material can be detected on the surface toindicate the location of production of the unwanted fluid.
 11. Awellbore penetrating a subterranean formation having a plurality of flowcontrol devices installed therein comprising: a first flow controldevice installed in the wellbore being actuable upon exposure to a firsttriggering chemical, but not upon exposure to a second triggeringchemical; and a second flow control device installed in the wellborebeing actuable upon exposure to the second triggering chemical, but notactuable upon exposure to the first triggering chemical.
 12. A wellboreaccording to claim 11 further comprising a third flow control deviceinstalled in a wellbore being actuable upon exposure to a thirdtriggering chemical, but not actuable upon exposure to the first andsecond triggering chemicals.
 13. A wellbore according to claim 11wherein each flow control device controls fluid flowing into thewellbore from a zone of the subterranean formation, the flow controldevices being arranged in a series within a portion of the wellbore, andan introduced triggering chemical flows to each of the flow controldevices so as to expose at least a portion of each flow control deviceto the introduced chemical.
 14. A wellbore according to claim 11 whereinthe first flow control device includes a mechanical stop retaining achoking member actuated with one or more spring members, and themechanical stop is dissolvable by the first triggering chemical but notby the second triggering chemical.
 15. A wellbore according to claim 11wherein the first triggering chemical causes an exothermic chemicalreaction within the first flow control device.
 16. A wellbore accordingto claim 11 wherein the first triggering chemical causes the release ofa plurality of sealing members that seal one or more orifices in thefirst flow control device.
 17. A wellbore according to claim 11 whereinthe first triggering chemical causes swelling of portions within thefirst flow control device so as to restrict fluid flow within the firstflow control device.
 18. A wellbore according to claim 11 furthercomprising a flowline to the first and second flow control devices, theflowline being separate from a production fluid flowline through whichfluid produced from the subterranean formation flows into the wellbore.19. A wellbore according to claim 11 wherein the first flow controldevice is associated with a first chemical tracer material and thesecond flow control device is associated with a second chemical tracermaterial, the first and second tracer materials being releasable in thepresence of an undesirable fluid.
 20. A wellbore according to claim 11wherein the wellbore includes a motherbore and a plurality of lateralwellbores branching from the motherbore, and wherein the first andsecond flow control devices are positioned within one of the lateralwellbores.
 21. A wellbore according to claim 11 wherein the firsttriggering chemical is located upstream from the first flow controldevice and is automatically released in the presence of an unwantedfluid, thereby automatically actuating the first flow control devicewithout human intervention or control.
 22. A wellbore according to claim21 wherein the first triggering chemical is encapsulated in a materialthat reacts or dissolves in the presence of the unwanted fluid and theencapsulating material can be detected on the surface to indicate thelocation of the production of the unwanted fluid.
 23. A wellboreaccording to claim 11 wherein the first flow control device includes anindicator chemical that is released into the wellbore when the device isactuated, the indicator chemical being detectable on the surface therebyindicating confirmation of actuation of the device.